Add: Git Demonstration reopen button

[tomi-neuron]

Amazing tool thank you very much! However I find myself having to go back to the Git Demonstration window often, to fully understand and apply the stuff explained there, but there is no easy way to do so. I have to reload the page and reopen the given session again in order to have a look at the short "class" on the present commands. Could you add a button on the bottom left alongside the others, to reopen the Git Description window again?

[pcottle]

Just try typing in `help level` to open up the level dialog again!